A lateral double diffused metal-oxide-semiconductor (LDMOS) is widely used in power devices due to its high breakdown voltage and compatibility with a complementary metal-oxide-semiconductor (CMOS) process. A source region and a drain region in a conventional MOS transistor are symmetrical relative to a gate. Compared with the conventional MOS transistor, a drain region in the LDMOS is farther from a gate than a source region. In the LDMOS, a long lightly doped region, called a drift region, is disposed between the drain region and the gate region. When the source region and the drain region are coupled with a high voltage, the LDMOS bears a high voltage drop through the drift region, to achieve a high breakdown voltage.
However, performance of the conventional LDMOS needs to be further improved.